What is the title of the first stage play credited to J.K. Rowling in the Harry Potter story world?

The first stage play credited to J.K. Rowling in the Harry Potter story world is Harry Potter and the Cursed Child.

The play was written by Jack Thorne and directed by John Tiffany, from an original story by Thorne, Tiffany, and Rowling. It premiered in London's West End in 2016. The story is set nineteen years after the events of Harry Potter and the Deathly Hallows and focuses on Harry's son Albus Severus Potter and Draco Malfoy's son Scorpius Malfoy.

The published script was released as Harry Potter and the Cursed Child Parts One and Two. It is a stage play rather than an eighth novel in Rowling's original seven-book series. That distinction explains why some readers describe it as a continuation of the story but not as the eighth Harry Potter book.